The present invention relates to agricultural machinery such as hay or vegetation windrowing machinery, and to a conveying belt having at least one working element attached exteriorly thereto for this purpose.
In agricultural machinery, it is sometimes advantageous to use power transmission belts for performing work in addition to their normal function of power transmission. One or more working elements, such as a crop cutter or crop gatherer, may be attached to the exterior of the belt. Examples of such devices appear in U.S. Pat. Nos. 2,305,044; 2,637,436; 2,728,181; 2,782,582; 2,867,069; 3,397,524; 3,545,188; 3,641,751; 3,651,626; 3,699,757; 3,831,358; 3,853,016; 3,896,611; 3,981,390; and 4,030,276. While such belts offer many advantages, they are not free of problems. Belts with cutters are driven at high speeds up to about 12,000 feet per minute to effect impact cutting, while belts with crop engaging fingers are driven up to a few hundred feet per minute to effect crop conveying.
Long belt spans are required for agricultural cutters or conveyors. The long spans and attached working elements may cause the belt to vibrate longitudinally or torsionally at such a frequency as to cause instability which may cause the belt to disengage from its sheaves. The instability caused by a twisting force on a working element may be reduced by locating the enter of gravity of the working element over the belt center with connectors extending through or from the belt center. However, such solution to the problem of belt stability also introduces design limitation. The cutter or other working element is purposely not offset from the edge of the belt to space the plane of the sheaves away from the foliage being cut or gathered. Such a displacement, the art teaches, offsets the center of gravity of the working element causing belt twisting.
For slow speed belts the problem is especially acute because the working element is typically larger which, because of an increased moment arm, makes it easily deflectable. Attempts have been made to attach working elements to the outer periphery of power transmission belts to enable design of an orbiting belt wherein the working element is displaced from the belt center. For example, U.S. Pat. No. 4,030,276 discloses a power transmission belt having one or more working elements attached to the exterior thereof. A portion of the working element extends transversely across and is attached to the belt at two connecting portions spaced and aligned transversely in relation to the belt. As another example, U.S. Pat. No. 3,981,390 discloses a belt having at least one longitudinally oriented groove into which is positioned a rib that extends from a foot portion of a working element. A single fastener extends through the belt and a portion of the foot. The groove, rib and fastener cooperate with each other to resist the foot from pivoting around the fastener.
While these patents offer some partial solutions to the problem of belt stability, they do not offer total solutions, but rather introduce some design limitations. The latter belt, in particular, requires additional or special belt building steps.
Accordingly, it is an object of the present invention to provide a belt-working element combination which is simple in construction and with a minimum of parts.
Another element of the invention is to provide a belt-working element combination which allows the center of gravity of the working element to be offset from the belt center without introducing instability to the belt.
Yet another object of the invention is to provide a hay rake which employs the belt-working element combination of this invention by moving this element in a novel pattern.
Other objects, aspects and advantages of the invention will be apparent to those skilled in the art after reviewing the following detailed description, the attached drawings and the appended claims.